use ptr diff rather than int

(cherry picked from commit 5b426038)

fix mem leak

(cherry picked from commit 603cb6cf)

check more table sizes

(cherry picked from commit 1828490b)

check cmap offset

(cherry picked from commit 683d9883)

check tableoffset against size

(cherry picked from commit ae73c3ff)

check ntables offset

(cherry picked from commit 75a171a4)

use safeint on calculations

(cherry picked from commit 139b6c6c)

simplify returns

(cherry picked from commit e8b2aad1)

extend to cover the last byte needed

(cherry picked from commit c7b0117f)

bounds check

(cherry picked from commit bb32616b)

move largest bounds check to start

(cherry picked from commit f832198e)

Change-Id: Ia174fd94c57cc3c899c10e1c0dc5968965a50427
0d329357ac282d4652b0f7ebc401cbd51963461b
004a6d322f60d916cc4635b362ce948e8a10d7c7
5aae26c38f3645020f0e1d6d7b6877c2727af1b4
a79be052dd3f6b6ed38fb326558924c853af5fff
d75f5f4b578fd176c17e5763569f1403260c6594
c063786ba41aa9a985f505e62b43d3d543a0d48f
1a67cb2f1c686032438852fec1267a59fbd04d7f
5177d42b47a4bca614878dce4a69ab16b5cfe163
6d32a6b6f1dd91db42a3f154700ea55603f0e4dd
03fe80f9568759b829fac4e9bcfd496efebe6a26
Reviewed-on: https://gerrit.libreoffice.org/49484Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>